Physics exam 3

A circular aluminum coil lies flat on a horizontal surface. A bar magnet is held above the center of the coil with its north pole pointing down. If the magnet is moved closer to the coil from this position, what is the direction of the induced current in the coil, as viewed from above as the magnet is moving? A) counterclockwise B) clockwise C) An emf but no current is induced in the coil. D) There is no current in the coil.

A

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades? A) The induced current flows counterclockwise. B) The induced current flows clockwise. C) There is no induced current in this coil. D) The current flows clockwise initially, and then it flows counterclockwise before stopping.

A

A photon of blue light and a photon of yellow light are traveling in vacuum. The photon of blue light A) has a smaller wavelength than a photon of yellow light and travels with the same speed. B) has a smaller wavelength than a photon of yellow light and travels with a greater speed. C) has a longer wavelength than a photon of yellow light and travels with the same speed. D) has a longer wavelength than a photon of yellow light and travels with a greater speed.

A

A photon of green light and a photon of red light are traveling in vacuum. The photon of green light A) has a smaller wavelength than a photon of red light and travels with the same speed. B) has a smaller wavelength than a photon of red light and travels with a greater speed. C) has a longer wavelength than a photon of red light and travels with the same speed. D) has a longer wavelength than a photon of red light and travels with a greater speed.

A

As more resistors are added in parallel across a constant voltage source, the power supplied by the source A) increases. B) decreases. C) does not change. D) increases for a time and then starts to decrease

A

If the wavelength of a photon is doubled, what happens to its energy? A) It is reduced to one-half of its original value. B) It stays the same. C) It is doubled. D) It is increased to four times its original value. E) It is reduced to one-fourth of its original value.

A

A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held above the center of the coil with its south pole downward. The magnet is moved toward the coil. As viewed from above, what is the direction of the current induced in the coil as the magnet approaches the coil? A) counterclockwise B) clockwise C) No current is induced in the coil. D) An emf but no current is induced in the coil.

B

A coil lies flat on a horizontal tabletop in a region where the magnetic field points straight down. The magnetic field disappears suddenly. When viewed from above, what is the direction of the induced current in this coil as the field disappears? A) counterclockwise B) clockwise C) clockwise initially, then counterclockwise before stopping D) There is no induced current in this coil.

B

A straight bar magnet is initially 4 cm long, with the north pole on the right and the south pole on the left. If you cut the magnet in half, the left half will A) contain only a north pole. B) contain a north pole on the right and a south pole on the left. C) contain only a south pole. D) no longer contain any poles.

B

A straight bar magnet is initially 4 cm long, with the north pole on the right and the south pole on the left. If you cut the magnet in half, the right half will A) contain only a north pole. B) contain a north pole on the right and a south pole on the left. C) contain only a south pole. D) no longer contain any poles.

B

As more resistors are added in series across a constant voltage source, the power supplied by the source A) increases. B) decreases. C) does not change. D) increases for a time and then starts to decrease.

B

Kirchhoff's junction rule is a statement of A) the law of conservation of momentum. B) the law of conservation of charge. C) the law of conservation of energy. D) the law of conservation of angular momentum. E) Newton's second law

B

Three identical capacitors are connected in series across a potential source (battery). If a charge of Q flows into this combination of capacitors, how much charge does each capacitor carry? A) 3Q B) Q C) Q/3 D) Q/9

B

When unequal resistors are connected in parallel across an ideal battery, A) the same power is dissipated in each one. B) the potential difference across each is the same. C) the current flowing in each is the same. D) the equivalent resistance of the sum of the individual resistances. E) the equivalent resistance of the circuit is equal to the average of all the resistances.

B

. If the wavelength of a photon is halved, what happens to its energy? A) It is reduced to one-half of its original value. B) It stays the same. C) It is doubled. D) It is increased to four times its original value. E) It is reduced to one-fourth of its original value.

C

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel with the first one, the time constant of the new RC circuit will be A) the same as before. B) twice as large as before. C) three times a large as before. D) one-half as large as before. E) one-fourth as large as before.

C

Three identical capacitors are connected in parallel to a potential source (battery). If a charge of Q flows into this combination, how much charge does each capacitor carry? A) 3Q B) Q C) Q/3 D) Q/9

C

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in the same direction, A) one wire is lifted slightly while the other wire is forced downward against the table's surface. B) both wires are lifted slightly. C) the wires pull toward each other. D) the wires push away from each other.

C

Two loops of wire are parallel to each other and close to each other. They have current passing through them in opposite directions. If the loops are allowed to move what will happen? A) Nothing B) Attract each other C) Repel each other D) Spin around each other E) Spin around shared axis.

C

When unequal resistors are connected in series across an ideal battery, A) the same power is dissipated in each one. B) the potential difference across each is the same. C) the current flowing in each is the same. D) the equivalent resistance of the circuit is less than that of the smallest resistor. E) the equivalent resistance of the circuit is equal to the average of all the resistances.

C

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in series with the first one, the time constant of the new RC circuit will be A) the same as before. B) twice as large as before. C) three times as large as before. D) smaller than before.

D

An electron is moving to the left in a magnetic field pointing toward the top of the page. What direction is the resulting force? A) top of page B) bottom of page C) into page D) out of page E) none of the above

D

An electron is moving to the right in a magnetic field pointing toward the bottom of the page. What direction is the resulting force? A) top of page B) bottom of page C) into page D) out of page E) none of the above

D

Two long parallel wires are placed side-by-side on a horizontal table. If the wires carry current in opposite directions, A) one wire is lifted slightly while the other wire is forced downward against the table's surface. B) both wires are lifted slightly. C) the wires pull toward each other. D) the wires push away from each other.

D

We observe that a moving charged particle experiences no magnetic force. From this we can definitely conclude that A) no magnetic field exists in that region of space. B) the particle must be moving parallel to the magnetic field. C) the particle is moving at right angles to the magnetic field. D) either no magnetic field exists, or the particle is moving parallel to the field. E) either no magnetic field exists, or the particle is moving perpendicular to the field.

D

Which one of the following types of electromagnetic wave travels through space the fastest? A) radio waves B) X-rays C) ultraviolet D) microwaves E) They all travel through space at the same speed.

E

Which one of the following types of electromagnetic wave travels through space the fastest? A) radio waves B) infrared C) gamma rays D) microwaves E) They all travel through space at the same speed.

E